Experimental and Numerical Investigation of the Impact of Swirl on the Performance of Industrial Gas Turbines Exhaust Diffusers

2003 ◽  
Author(s):  
V. Vassiliev ◽  
S. Irmisch ◽  
M. Claridge ◽  
D. P. Richardson
Keyword(s):  
Mach Number ◽  
Gas Turbines ◽  
Modular Design ◽  
Numerical Procedure ◽  
Angle Distribution ◽  
Flow Angle ◽  
Industrial Gas Turbines ◽  
Inlet Swirl ◽  
Inlet Conditions ◽  
The Impact

In order to investigate the effect of inlet conditions on the performance of an axial strutted annular exhaust diffuser, as used in heavy duty gas turbines, a scaled test-rig was built which allows the systematic variations of inlet conditions like inlet swirl, Mach number and turbulence level. This rig, which is of modular design, is used for the analysis of the flow-structures in typical GT-exhaust configurations and provides the performance data used in the diffuser design process. The present work shows the influence of inlet swirl and Mach number on the performance of a specific diffuser configuration. The first strut was designed for a certain flow angle distribution (so-called design conditions), and the measurements have been done for a range of inflow parameters including design and off-design conditions. The measurements allowed to reveal the impact of 3D effects on the diffuser characteristic. Comparison of measurements with correlations available from literature (annular diffuser configurations) show that the application of the latter is of limited use for the design of real GT diffusers, because standard correlations do not account for inlet swirl / struts interaction. The experimental data has been used to validate the numerical procedure developed by the authors for the analysis of axial GT exhaust diffusers. The results of computations are in reasonable agreement with measurements.

Effect of Unguided Turning Angle and Trailing Edge Shape on Cooled Blade Loss

2014 ◽  
Author(s):  
Andrey Granovskiy ◽  
Mikhail Kostege ◽  
Vladimir Vassiliev
Keyword(s):  
Gas Turbines ◽  
Numerical Procedure ◽  
Suction Side ◽  
Aerodynamic Characteristics ◽  
Base Pressure ◽  
Trailing Edge ◽  
Flow Angle ◽  
Generation Mechanisms ◽  
Cooled Blade ◽  
Blade Loss

A significant part of the overall loss in modern gas turbines is the trailing edge loss. This loss is, more strongly than other constituents, affected by operation, because the trailing edge can significantly change its shape due to degradation. Also by manufacturing of new parts and reconditioning the same tolerances as in other parts of blade lead to higher deviations of aerodynamic characteristics. Therefore the understanding of trailing edge loss generation mechanisms is of utmost importance for a sound blade design. In this work the results of combined experimental and numerical investigation of the trailing edge impact on the transonic cooled blade loss are presented. This study comprises the investigation of the unguided flow angle and the trailing edge shape on the profile losses and a base pressure. The unguided flow angle characterizes the curvature distribution on the aerofoil suction side. The numerical and experimental investigation of transonic cooled turbine cascades have shown that the increase of the unguided flow angle results in loss reduction due to increase of the base pressure downstream of the trailing edge. At the same time the deviation of the trailing edge from a round shape has detrimental effect on performance and conducted investigations allow quantification of this effect. The measurements were performed in a transonic wind tunnel and numerical simulations were done using in-house 2D Navier-Stokes code. The comparison of calculations with measurements showed that they are in reasonable agreement. The validated numerical procedure has been used for demonstration of possibility to reduce loss in aerofoil with thick trailing edge by tuning of the unguided flow angle. The use of the thick trailing edges at HP cooled turbines reduces restriction on tolerances, improves of manufacturability and reduces cost.

scholarly journals Industrial Gas Turbine Performance: Compressor Fouling and On-Line Washing

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Uyioghosa Igie ◽  
Pericles Pilidis ◽  
Dimitrios Fouflias ◽  
Kenneth Ramsden ◽  
Panagiotis Laskaridis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Operating Conditions ◽  
Compressor Cascade ◽  
Compressor Blades ◽  
Turbine Performance ◽  
Industrial Gas Turbines ◽  
On Line ◽  
The Impact

Industrial gas turbines are susceptible to compressor fouling, which is the deposition and accretion of airborne particles or contaminants on the compressor blades. This paper demonstrates the blade aerodynamic effects of fouling through experimental compressor cascade tests and the accompanied engine performance degradation using turbomatch, an in-house gas turbine performance software. Similarly, on-line compressor washing is implemented taking into account typical operating conditions comparable with industry high pressure washing. The fouling study shows the changes in the individual stage maps of the compressor in this condition, the impact of degradation during part-load, influence of control variables, and the identification of key parameters to ascertain fouling levels. Applying demineralized water for 10 min, with a liquid-to-air ratio of 0.2%, the aerodynamic performance of the blade is shown to improve, however most of the cleaning effect occurred in the first 5 min. The most effectively washed part of the blade was the pressure side, in which most of the particles deposited during the accelerated fouling. The simulation of fouled and washed engine conditions indicates 30% recovery of the lost power due to washing.

scholarly journals Influence of Rim Seal Geometry on Hot Gas Ingestion Into the Upstream Cavity of an Axial Turbine Stage

1999 ◽  
Author(s):  
Dieter Bohn ◽  
Bernd Rudzinski ◽  
Norbert Sürken ◽  
Wolfgang Gärtner
Keyword(s):  
Mach Number ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Main Flow ◽  
Rotor Blades ◽  
Flow Rates ◽  
Hot Gas ◽  
Carbon Dioxide Gas ◽  
Industrial Gas Turbines ◽  
Rotor Disk

The ingestion of hot gas at the rim seal of a turbine has been investigated for a complete stage with nozzle guide vanes and rotor blades for two types of geometry: 1. the simple axial gap between a flat rotor disk and a flat stator disk, commonly used for industrial gas turbines and 2. an axial lip of the rim seal on the stator combined with a flat rotor disk, often found in aero engine applications. The clearance of the axial gap has been varied for the second type. The efficiency of the rim seal has been examined for different seal flow rates, rotational Reynolds numbers and Mach numbers in the main flow. For the determination of the sealing effectiveness carbon dioxide gas concentration measurements have been carried out in the wheelspace. The distribution of the static pressure in the vicinity of the seal and inside the wheelspace has been measured by means of pressure taps at the stator disk. It is shown that the external flow Mach number in the main flow has a significant effect on the sealing efficiency. As Mach number increases sealing efficiency goes down. The rotational Reynolds number has a distinct effect on the rim seal efficiency depending on the examined configuration. Even for high seal flow rates the ingestion of hot gas can not be fully avoided. The experimental results were the motivation for a three-dimensional CFD approach neglecting the influence of the rotor blades. The results give further insight into aerodynamic features of the ingestion phenomenon.

Dry, Low Emissions for the ‘H’ Heavy-Duty Industrial Gas Turbines: Full-Scale Combustion System Rig Test Results

2003 ◽  
Author(s):  
Geoff Myers ◽  
Dan Tegel ◽  
Markus Feigl ◽  
Fred Setzer ◽  
William Bechtel ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Full Scale ◽  
Combustion System ◽  
Heavy Duty ◽  
Test Program ◽  
Industrial Gas Turbines ◽  
Inlet Conditions

The lean, premixed DLN2.5H combustion system was designed to deliver low NOx emissions from 50% to 100% load in both the Frame 7H (60 Hz) and Frame 9H (50 Hz) heavy-duty industrial gas turbines. The H machines employ steam cooling in the gas turbine, a 23:1 pressure ratio, and are fired at 1440 C (2600 F) to deliver over-all thermal efficiency for the combined-cycle system near 60%. The DLN2.5H combustor is a modular can-type design, with 14 identical chambers used on the 9H machine, and 12 used on the smaller 7H. On a 9H combined-cycle power plant, both the gas turbine and steam turbine are fired using the 14-chamber DLN2.5H combustion system. An extensive full-scale, full-pressure rig test program developed the fuel-staged dry, low emissions combustion system over a period of more than five years. Rig testing required test stand inlet conditions of over 50 kg/s at 500 C and 28 bar, while firing at up to 1440 C, to simulate combustor operation at base load. The combustion test rig simulated gas path geometry from the discharge of the annular tri-passage diffuser through the can-type combustion liner and transition piece, to the inlet of the first stage turbine nozzle. The present paper describes the combustion system, and reports emissions performance and operability results over the gas turbine load and ambient temperature operating range, as measured during the rig test program.

Increasing Diagnostic Effectiveness by Inclusion of Fuel Composition and Water Injection Effects

2002 ◽  
Author(s):  
K. Mathioudakis ◽  
N. Aretakis ◽  
A. Tsalavoutas
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Water Injection ◽  
Diagnostic Technique ◽  
Diagnostic Methods ◽  
Working Fluid ◽  
Fluid Properties ◽  
Industrial Gas Turbines ◽  
The Impact ◽  
Engine Condition

The paper presents an analysis of the effect of changing the fuel on the performance of industrial gas turbines and examines the impact of such a change on methods used for engine condition assessment and fault diagnostics. A similar analysis is presented for the effects of water injection in the combustion chamber (which is usually done for reducing NOx emissions). First, the way of incorporating the effect of fuel changes and water injection into a computer model of gas turbine performance is described. The approach employed is based on the change of (a) working fluid properties, (b) turbomachinery components performance. The model is then used to derive parameters indicative of the “health” of a gas turbine and thus diagnose the presence of deterioration or faults. The impact of ignoring the presence of an altered fuel or injected water is shown to be of a magnitude that would render a diagnostic technique that does not incorporate these effects ineffective. On the other hand, employing the appropriate physical modeling makes the diagnostic methods robust and insensitive to such changes, being thus able to provide useful diagnostic information continuously during the use of a gas turbine.

Numerical Procedure for the Investigation of Combustion Dynamics in Industrial Gas Turbines: LES, RANS and Thermoacoustics

2015 ◽  
Author(s):  
Luca Rofi ◽  
Giovanni Campa ◽  
Vyacheslav Anisimov ◽  
Federico Daccá ◽  
Edoardo Bertolotto ◽  
...  
Keyword(s):  
Experimental Data ◽  
Gas Turbines ◽  
Numerical Procedure ◽  
Combustion System ◽  
Combustion Dynamics ◽  
Eddy Simulation ◽  
Experimental Apparatus ◽  
Industrial Gas Turbines ◽  
Computationally Intensive ◽  
Acoustic Instabilities

The necessity for a combustion system to work with premixed flames and its capability to cope with rapid load variations avoiding the occurrence of thermo-acoustic instabilities, has led to investigate the complex dynamic phenomena that occur during combustion. Thanks to numerical simulations it is possible to examine these complex mechanisms getting useful information to optimize the combustion system. The aim of this work is to describe a numerical procedure developed in Ansaldo Energia for the investigation of combustion dynamics occurring in Ansaldo Energia gas turbines. In this paper, firstly the experimental apparatus of a full scale atmospheric test rig equipped with Ansaldo Energia burner is described. Secondly, the flame behavior is studied by means of a Large Eddy Simulation (LES). Once the LES has reached a statistically stationary state, a forcing is added to the system to compute the Flame Transfer Function (FTF), in terms of amplitude n and delay time τ, related to initial phases of humming. Thirdly, the forced flame simulations are used as the input of an Helmholtz solver to analyze the acoustic behavior of the system, which is then compared to experimental data. Finally, to evaluate the feasibility of a less computationally intensive approach, a RANS simulation of the same configuration is described and the results are transferred to FEM (Finite Element Method) Helmholtz solver: a comparison between the LES approach and the RANS approach is carried out with reference to the experimental data.

A Sensitivity Study of Gas Turbine Exhaust Diffuser-Collector Performance at Various Inlet Swirl Angles and Strut Stagger Angles

2017 ◽  
Author(s):  
Michal P. Siorek ◽  
Stephen Guillot ◽  
Song Xue ◽  
Wing F. Ng
Keyword(s):  
Gas Turbine ◽  
Flow Direction ◽  
Flow Behavior ◽  
Exhaust System ◽  
Sensitivity Study ◽  
Inlet Swirl ◽  
Inlet Conditions ◽  
Gas Turbine Exhaust ◽  
The Impact ◽  
Turbine Exhaust

This paper describes studies completed using a quarter-scaled rig to assess the impact of turbine exit swirl angle and strut stagger on a turbine exhaust system consisting of an integral diffuser-collector. Advanced testing methods were applied to ascertain exhaust performance for a range of inlet conditions aerodynamically matched to flow exiting an industrial gas turbine. Flow visualization techniques along with complementary Computational Fluid Dynamics (CFD) predictions were used to study flow behavior along the diffuser endwalls. Complimentary CFD analysis was also completed with the aim to ascertain the performance prediction capability of modern day analytical tools for design phase and off-design analysis. The K-Epsilon model adequately captured the relevant flow features within both the diffuser and collector, and the model accurately predicted the recovery at design conditions. At off-design conditions, the recovery predictions were found to be pessimistic. The integral diffuser-collector exhaust accommodated a significant amount of inlet swirl without a degradation in performance, so long as the inlet flow direction did not significantly deviate from the strut stagger angle. Strut incidence at the hub was directly correlated with reduction in overall performance, whereas the diffuser-collector performance was not significantly impacted by strut incidence at the shroud.

A Preliminary Numerical CFD Analysis of Transonic Compressor Rotors When Subjected to Inlet Swirl Distortion

2011 ◽  
Author(s):  
Javier Castaneda ◽  
Ahad Mehdi ◽  
Domenico di Cugno ◽  
Vassilios Pachidis
Keyword(s):  
Vortex Core ◽  
High Performance ◽  
Preliminary Investigation ◽  
Angle Distribution ◽  
Transonic Compressor ◽  
Aspect Ratios ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
System Life ◽  
The Impact

A preliminary investigation of a CFD capability to assess the impact of inlet swirl distortion on transonic compressor rotors has been carried out. In the late 1960s with the advent of turbo fan engines, industry and government agencies became increasingly aware of the inlet total pressure distortion problem. Since then, the inlet/engine compatibility assessment has become a significant issue within the propulsion system life cycle. Nowadays the development of high-performance military aircraft and UAV with maneuvers before unthinkable, entail considerable levels of inlet flow angularity. The importance of developing a rigorous methodology to understand the effect of inlet swirl distortion on turbomachinery has also become one of the major concerns of present day. NASA rotor 67 and 37 were selected for this investigation having different hub to tip radius and aspect ratios. The steady state CFD simulations were carried out on two types of inlet swirl distortion scenarios: Bulk swirl (both Rotor 37 and 67) and Ground vortex (only Rotor 67). A parametric study to define the swirl angle distribution for ground vortex cases was also accomplished. The non-dimensional ground clearance, wind conditions and core vortex location at the inlet/engine AIP were the parameters taken into account. The study carried out suggests that ground vortex core location and vortex rotational direction greatly affect the shift of the speedline. This emphasizes the importance of identifying the radial location of ingested vortex core at the AIP as the turbomachinery response differs depending on it. Similar shift in speedlines for the bulk swirl cases were also observed.

A Sensitivity Study of Gas Turbine Exhaust Diffuser-Collector Performance at Various Inlet Swirl Angles and Strut Stagger Angles

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Michal P. Siorek ◽  
Stephen Guillot ◽  
Song Xue ◽  
Wing F. Ng
Keyword(s):  
Gas Turbine ◽  
Flow Direction ◽  
Flow Behavior ◽  
Exhaust System ◽  
Sensitivity Study ◽  
Inlet Swirl ◽  
Inlet Conditions ◽  
Gas Turbine Exhaust ◽  
The Impact ◽  
Turbine Exhaust

This paper describes studies completed using a quarter-scaled rig to assess the impact of turbine exit swirl angle and strut stagger on a turbine exhaust system consisting of an integral diffuser-collector. Advanced testing methods were applied to ascertain exhaust performance for a range of inlet conditions aerodynamically matched to flow exiting an industrial gas turbine. Flow visualization techniques along with complementary computational fluid dynamics (CFD) predictions were used to study flow behavior along the diffuser end walls. Complimentary CFD analysis was also completed with the aim to ascertain the performance prediction capability of modern day analytical tools for design phase and off-design analysis. The K-Epsilon model adequately captured the relevant flow features within both the diffuser and collector, and the model accurately predicted the recovery at design conditions. At off-design conditions, the recovery predictions were found to be pessimistic. The integral diffuser-collector exhaust accommodated a significant amount of inlet swirl without degradation in performance, so long as the inlet flow direction did not significantly deviate from the strut stagger angle. Strut incidence at the hub was directly correlated with reduction in overall performance, whereas the diffuser-collector performance was not significantly impacted by strut incidence at the shroud.

An Evaluation of the Effects of Water Injection on Compressor Performance

2003 ◽  
Author(s):  
A. J. White ◽  
A. J. Meacock
Keyword(s):  
Gas Turbines ◽  
Evaporative Cooling ◽  
Water Injection ◽  
Compression Process ◽  
Compressor Inlet ◽  
Design Behaviour ◽  
Industrial Gas Turbines ◽  
Compressor Performance ◽  
Compressor Work ◽  
The Impact

The injection of water droplets into compressor inlet ducting is now commonly used as a means of boosting the output from industrial gas turbines. The chief mechanisms responsible for the increase in power are the reduction in compressor work per unit flow and the increase in mass flow rate, both of which are achieved by evaporative cooling upstream of and within the compressor. This paper examines the impact of such evaporative processes on compressor operation, focussing particular attention on cases with substantial over-spray — i.e., for which significant evaporation takes place within the compressor itself, rather than in the inlet. A simple numerical method is described for the computation of wet compression processes, based on a combination of droplet evaporation and mean-line calculations. The method is applied to a “generic” compressor geometry in order to investigate the nature of the off-design behaviour that results from evaporative cooling. Consideration is also given to the efficiency of the compression process, the implications for choking and stall, and the magnitude of the thermodynamic loss resulting from irreversible phase change.

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